The present invention relates to an improved fastener device for belt fastening, and more particularly to a fastener device in which the pressing latch boards of the male fastener are prevented from being withdrawn and unlocked from the latch seat of the female fastener by unexpected external force to provide a reliable locking effect.
A conventional fastener device is shown in FIGS. 1 and 2, wherein the fastener device includes a male fastener 1 having an engaging portion 11 and a female fastener 2 having an engaging portion 21. A pair of pressing latch boards 12 are disposed at a front section of the engaging portion 11 of the male fastener 1. Each pressing latch board 12 has an inward projecting engaging latch lug 121. A guide block 13 is integrally formed on the male fastener 1 between the latch lugs 121. The female fastener 2 has a front latch seat 25. Two latch sockets 24 are formed on two sides of the latch seat 25 respectively. A slidable lock device 3 having a push botton 31 exposed on an tip of the femake fastener 2, is disposed on the latch seat 25 in a receptacle 23 of the female fastener 2. On two sides of the lock button 3 beside the receptacle 23 are disposed two L-shaped lock blocks 22. When the male fastener 1 is fitted into the latch seat 25 of the female fastener 2, the guide block 13 of the male fastener 1 is smoothly inserted into the receptacle 23 of the female fastener 2 with the pressing latch board 12 locked in the latch socket 24 of the latch seat 25. At this time, the channels 14 of the pressing latch board 12 are engaged with the lock blocks 22 of the female fastener 2. As shown in FIGS. 1 and 2, the slidable lock device 3 in the latch seat 25 of the female fastener 2 is pushed forward to make the lock blocks 22 of the slidable lock device 3 abut against the latch lugs 121 of the pressing latch board 13 of the male fastener 1 so that the pressing latch board 12 is not easy to be pressed inward by external force. Reversely, when the push button 31 of the slidable lock device 3 is pushed backward to make the latch lugs 121 disengaged from the engaging blocks 31, the pressing latch board 12 of the male fastener 1 can be pressed inward by external force and thus the male fastener 1 can be detached from the latch seat 25 of the female fastener 2. According to the above arrangements, several shortcomings in use exist as follows:
1. While the push button 32 of slidable lock device 3 is exposed on an outside of the fastener surface. It will easily be moved to unlocked position by unexpected external force.
2. When the latch lugs 121 of the pressing latch board 12 of the male fastener 1 are engaged with the engaging blocks 31 of the lock button 3 of the female fastener 2 in a locked state. If a raging force is exerted onto the pressing latch board 12, the slidable lock device 3 will be forced to move backward into an unlocked state.
3. In case a raging force is exerted onto the pressing latch board 12, the latch lugs 121 will be broken to lose the locking function.
4. The conventional fastener device is relatively complicated in structure and the mold therefor cannot be easily made. This results in higher manufacturing cost.